Oil well pumping systems are well known in the art. Such systems are used to mechanically remove oil or other fluid from beneath the earth's surface, particularly when the natural pressure in an oil well has diminished. As shown in FIG. 22, an oil well pumping system begins with an above-ground pumping unit 102, which may commonly be referred to as a “pumpjack,” “nodding donkey,” “horsehead pump,” “beam pump,” “sucker rod pump,” and the like. The pumping unit 102 creates a reciprocating (up and down) pumping action that moves the oil (or other substance being pumped) out of the ground 100 and into a flow line, from which the oil is then taken to a storage tank or other such structure.
Below the ground 100, a shaft is lined with piping 104 known as “tubing.” Into the tubing 104 is inserted a string of sucker rods 106, which ultimately is indirectly coupled at its north end to the above-ground pumping unit 102. The string of sucker rods 106 is ultimately indirectly coupled at its south end to a subsurface pump 108 that is located at or near the fluid in the oil well. As shown in FIG. 23, the subsurface pump 108 has a number of basic components, including a barrel 110 and a plunger 112. The plunger 112 operates within the barrel 110, and the barrel 110, in turn, is positioned within the tubing 104. It is common for the barrel 110 to include a standing valve 114 and the plunger 112 to include a traveling valve 116. The north end of the plunger 112 is typically connected to a valve rod 118, hollow valve rod 118, or pull tube, which moves up and down to actuate the pump plunger 112. The valve rod 118, hollow valve rod 118, or pull tube passes through a guide 120 positioned at the north end of the barrel 110, which assists in centering the valve rod 118, hollow valve rod 118, or pull tube, and thereby, the plunger 112. In addition, the guide 120 includes openings through which the oil (or other substance being pumped) may exit the pump barrel 110 and travel into the tubing 104.
There are a number of problems that may occur during oil pumping operations. Fluid that is pumped from the ground 100 is generally impure, and includes solid impurities such as sand, pebbles, limestone, and other sediment and debris. Certain kinds of pumped fluids, such as heavy crude, tend to contain a relatively large amount of solids. Because of this, several disadvantages exist with prior art guides 120 for valve rods 118, hollow valve rods 118, and pull tubes. For example, the orientation of the side openings in such prior art guides 120 permits fluid, and any solid impurities entrained therein, to shoot straight out in the direction of the pump barrel 110 when it is expelled from the guide 120. This causes damage to the barrel 110 due to the high velocity of the fluid during pumping operations. Further, after the solids have been exhausted from the pump barrel 110 and the pump 102 has temporarily discontinued pumping operations, the solids will naturally begin to settle due to gravity. With prior art guides 120 for valve rods 118, hollow valve rods 118, and pull tubes, the solids are able to reenter the pump barrel 110 at this time, via the openings in the guide 120. This often results in excessive barrel 110 wear upon restarting of the pump 102. Further, it is possible that with the solids reentering the pump barrel 110, they may cause sticking of the pump 102—i.e., seizing the plunger 112 in the barrel 110.
As another example, solids often cling to valve rods 118, hollow valve rods 118, and pull tubes during pumping operations. Typically, with prior art guides 120 for valve rods 118, hollow valve rods 118, and pull tubes, this can result in the binding or seizing of the guide 120 to the valve rod 118, hollow valve rod 118, or pull tube that is moving up and down actuating the pump plunger 112. This seizing can cause the pump 102 to stop functioning, by preventing the valve rod 118, hollow valve rod 118, or pull tube from being actuated, thereby damaging the sucker rod 106 and guide 120.
As another example, the north ends of prior art guides 120 for valve rods 118, hollow valve rods 118, and pull tubes are frequently subjected to excessive wear and damage by virtue of the sucker rod 106 activity. In this regard, the sucker rod 106 is attached proximate the north end of the valve rod 118, hollow valve rod 118, or pull tube (whichever is being employed). The sucker rod 106 sometimes carries side loads when the pump 102 is in a downward stroke. The side loads can impart excessive wear and damage on the side of the guide 120 for the valve rod 118, hollow valve rod 118, or pull tube, rendering the guide 120 useless.
A need therefore exists for a guide 120 for a valve rod 118, hollow valve rod 118, and pull tube that provides for improved debris removal capability and wear resistance.
The present invention satisfies these needs and provides other, related, advantages.